1. CS-328 A Networking Primer
Internet Programming
TCP/IP
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2. OSI Network Model 7 6 5 4 3 2 1 Application Layer Presentation Layer
Provides the interface to a set of network-wide services.
Provides such services as: file transfer access and management, document and
Message interchange, job transfer, etc. 6
Presentation
Layer
Provides a syntax independent message interchange service.
Provides for data representation conversion and syntax negotiation. 5
Session
Layer
Provides the control structure for communication between applications.
Establishes, manages, and terminates sessions between applications. 4
Transport
Layer
Provides a message transfer facility independent of underlying network.
Provides for end-to-end message transfer.
Deals with connection management, fragmentation, flow control, error control. 3
Network
Layer
Breaks data into information packets.
Provides a virtual packet carrying end-to-end connection.
Deals with routing, addressing, call setup, buffering, and flow control. 2
Data Link
Layer
Breaks data into information frames.
Provides a data link that is free of undetected transmission errors.
Deals with framing, data transparency, error control, flow control 1
Physical
Layer
Deals with bits. Provides a virtual bit pipe.
Provides for the transmission of bit streams over physical medium.
Deals with mechanical, electrical, functional, & procedural aspects of medium.
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3. LANs Local Area Networks Layers 1 and 2 of the OSI model
A collection of peer computers connected together with a common wire protocol
Ethernet
Token Ring
for the purpose of local communications
Printer sharing
File sharing
Usually connected together in the same geographical area
Each host identified by its Media Access Control (MAC) address
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4. 2 Peers Connected TogetherPC
NIC
NIC PC R R
Crossover Cable
Peer Connections like this are ok for connecting two computers together, connecting additional computers together requires the creation of a Local Area Network (LAN)
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5. LAN ethernet ethernet ethernet HUB STAR Topology ethernet ethernet
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6. Ethernet (CSMA/CD) Polite Human Communication
Listen before speaking, if someone else is speaking wait for them to finish
While speaking, if someone else starts speaking, stop speaking
This collision detection
Carrier Sense Multi Access w/Collision Detection
Carrier Sense is how you tell if someone else is already talking
While sending, listen to the receive if you hear someone a collision is occurring so hold off and try later
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7. Ethernet Cable
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8. An internetwork
LAN
LAN
LAN
LAN
WAN LA
LAN
LAN
LAN
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9. Internetworks A network of networks Hubs let you build LANs
To join LANs into a WAN requires a device that works at the Network Layer of the OSI model to bridge the multiple networks
This is usually an IP Router
Could also be a Switch or a Bridge
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10. TCP/IP Transmission Control Protocol and Internet Protocol (TCP/IP)
software suite that enables a single, standards based approach to communications for a heterogeneous wide area network
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11. Layering Network protocols are usually developed in layers
TCP/IP protocol suite is a combination of a set of protocols operating at the various layers
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12. TCP/IP Layers Application Telnet, FTP, SMTP.... Transport TCP, UDP
Network
IP, ICMP,IGMP
Link
device driver and interface card ARP/RARP
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13. Link Layer
Handles all of the details of physically connecting a machine to the network
network card
device driver for the card
operating system
Protocols
Address Resolution Protocol (ARP)
Reverse Address resolution Protocol (RARP)
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14. NetworkLayer handles the movements of packets around the network
routing takes place in the network layer
protocols
Internet Protocol (IP)
Internet Control Message Protocol (ICMP)
Internet Group Management Protocol (IGMP)
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15. Transport Layer
provides a flow of data between two hosts for the application layer
Transmission Control Program (TCP)
Reliable Delivery System
User Datagram Protocol (UDP)
also known as Unreliable Datagram Protocol
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16. Application Layer handles details of the particular application
common applications:
Telnet for remote login
File Transfer Protocol (FTP)
Simple Mail Transfer Protocol (SMTP)
Simple Network Management (Protocol)
Ping
DateTime
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17. TCP and UDP TCP UDP reliable data flow connection based
receipt acknowledgement
packet sizing
timeouts
checksuming
connection based
telephone metaphor
call another host
caller knows if answered
UDP
sends datagrams (packets) fast
no guarantees
connectionless
mailbox metaphor
datagram is a letter
put letter into mailbox
hope someone picks it up
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18. TCP Frame 16 bit Source Port number 16 bit Destination Port Number
32 bit Sequence Number
32 bit Acknowledgement Number
4 bit Data Offset
6 bit reserved
1 bit Urgent Flag (URG)
1 bit Acknowledgement Field is valid (ACK)
1 bit Push Function (PSH)
1 bit Reset connection (RST)
1 bit Synchronized sequence numbers (SYN)
1 bit No more data from sender (FIN)
16 bit Window field (# of bytes sender is willing to accept)
16 bit checksum (one’s complement sum of all 16 bit words in the header and data)
16 bit urgent pointer (add to sequence # of this segment, this pointer to last octet of urgent data
options -
padding
data
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19. TCP Connection - Establish
TCP establishes a connection between two hosts by performing a 3-way handshake, this will establish a virtual connection between the two hosts
Host 1
Host 2
Network Messages
Send SYN seq=x
Receive SYN segment
Send SYN seq=y, ACK x+1
Receive SYN + ACK segment
Send ACK y+1
Receive ACK Segment
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20. TCP Connection - Closing
Network Messages
Send FIN seq=x
Receive FIN segment
Send ACK x+1
Receive ACK segment
Send FIN ,ACK seq=x+1
Receive FIN + ACK segment
Send ACK y+1
Receive ACK Segment
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21. Client/Server and TCP/IP
FTP Protocol
FTP Client
FTP Server
TCP Protocol
TCP
TCP
IP Protocol IP IP
Ethernet Protocol
Ethernet driver
Ethernet driver
Ethernet
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22. IP Routing and protocol conv.
FTP Protocol
FTP Client
FTP Server
TCP Protocol
TCP
TCP
Router
IP Protocol
IP Protocol IP IP IP
Ethernet driver
Ethernet driver
Token ring driver
Token ring Driver
Ethernet
Token Ring
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23. A Clearer Picture User Process User Process User Process User Process
Application
TCP
UDP
Transport
ICMP IP
IGMP
Network
Hardware Interface
ARP
RARP
Link
media
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24. Internet Addresses (IPv4)
32 bit number
written as 4 decimal numbers seperated by periods (dotted decimal notation)
Five classes of internet addresses
class A thru class E
netid are issued by InterNIC (Internet Network Information Center) also registers domain names
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25. Class A 0.0.0.0 thru 127.255.255.255 7 bits 24 bits netid hostid
netid
hostid
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26. Class B 128.0.0.0 thru 191.255.255.255 14 bits 16 bits 10 netid hostid
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27. Class C 192.0.0.0 thru 223.255.255.255 21 bits 8 bits 110 netid hostid
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28. Class D 224.0.0.0 thru 239.255.255.255 28 bits 1110 multicast group id
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29. Class E
thru
27 bits
11110
reserved for future use
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30. IPv6 (IPng) 128 bit number 3 types of addresses
written as 8 decimal numbers separated by colons
3 types of addresses
Unicast - a packet sent to a unicast address is delivered to the interface identified by that address
Anycast - an identifier for a set of interfaces(typically belonging to different nodes). A packet sent to an anycast address is delivered to one of the interfaces identified by the address (the “nearest” identified by the routing protocol’s measure of distance)
Multicast - An identifier for a set of interfaces ( typically belonging to different nodes). A packet sent to a multicast address will be delivered to all interfaces identified by that address.
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31. IPv6 Text representation of Addresses
Preferred form:
x:x:x:x:x:x:x:x
where each x represents a 4 hexadecimal digit 16-bit piece of the address
FEDC:BA89:7654:3210:FEDC:BA98:7654:3210
1080:0:0:0:8:800:200C:417A
note - leading zeros are not required
note- pieces consisting of all zero bits may be shown as ::
Alternative form
sometimes used in mixed IPv4 and IPv6 environments
x:x:x:x:x:x:d.d.d.d
where x represents high order 6 pieces of IPV6 address and the 4 d’s represent the IPv4 address
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32. IPv4 to IPv6 transition
For tunneling IPV6 packets through an IPv4 infrastructure use:
IPv4-compatible IPv6 address (special IPv6 unicast address that contain the IPv4 address)
80 bits
16bits
32 bits
0000………………………………………… IPv4 address
For nodes that are IPv4 only (do not support IPv6) use:
IPv4-mapped IPv6 address
80 bits
16bits
32 bits
0000………………………………………… FFFF IPv4 address
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33. Domain Name System (DNS)
Distributed database
provides translation between IP addresses and hostnames (and vice-versa)
Most TCPIP Applications can use either way of identifying a host (i.e. by host name or IP address)
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34. Encapsulation user data Application App.Hdr user data Transport
TCP Hdr
App.Hdr
user data
Network
IP Hdr
TCP Hdr
App.Hdr
user data
Link
ethernet hdr
ethernet trailer
IP Hdr
TCP Hdr
App.Hdr
user data
ethernet frame
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35. Ports and Sockets mean the same thing, part of a buffering scheme
implemented at transport layer (TCP/UDP)
16 bit number in the TCP or UDP header (32767 connection possible)
ports 1 thru 1023 reserved for “well known ports”
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36. Well Known Ports ports used for common TCP/IP applications
TCP port 7 - Echo
TCP port 20 - FTP-Data
TCP port FTP-Commands
TCP port telnet
UDP port 67 - BOOTP (Server)
UDP port 68 - BOOTP (Client)
UDP port 69 - TFTP
etc
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37. Java and sockets supports both TCP and UDP sockets
also multicast under RMI
provided both ends of a TCP application connection (i.e. client and server facilities)
java.net
also provides URL connections
can be used to implement almost any existing internet protocol.
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38. Java Sockets create a socket create an input stream
create an output stream
connect the inputstream to the socket
connect the output stream to the socket
reading and writing the stream transfers data between the two hosts (local and remote)
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